The Gaelic vowels are divided into two classes—broad and small. The broad vowels are a, o, u: the small, e, i. The Gaelic diphthongs14 represent (1) simple sounds, (2) real diphthong sounds, or (3) modification of the consonants and carrying out of the law of “broad to broad and small to small.” They are as follows:—
| ai, ao, [au][1] | ài |
| ea, ei, eo, eu, eò | éi, èi |
| ia, io, iu, iù | ìo |
| oi, [ou][1] | òi |
| ua, ui | ùi |
Here ea, ei, eu represent O. Ir. e, é, and are practically simple sounds, as certainly is ao. The forms ia, ua are genuine diphthongs, as are usually the long vowel combinations. The rest may be diphthongs, or may be a trick of spelling, as in the word fios (O. Ir. fis), where the o shows that the s has its normal sound, and not that of E. sh, as fis would imply.
Triphthongs occur in the course of inflection, and in the case of ao otherwise. These are—aoi, eoi, iai, iui, uai, eòi, iùi.
The consonants are classified in accordance with the position of the organs of speech concerned in their utterance:—
I. Liquids.—The liquids are l and r, with the nasals n and m. In writing, m only is “aspirated,” becoming to the eye mh, to the ear a v with nasal influence on the contiguous vowels. The other liquids, l, n, and r, are really aspirated in positions requiring aspiration, though no h is attached to show it.15 There is, however, only a slight change of sound made in these letters by the aspiration—a more16 voiced sound being given them in the aspirating position.
II. Mutes and Explosives.—These all suffer aspiration when intervocalic. They are classified as follows:—
| Tenues. | Mediæ. | Aspirates. | |
| Labials | p | b | ph, bh |
| Dentals | t | d | th, dh |
| Gutturals | c | g | ch, gh |
The dentals d and t become spirants17 when in contact with, or flanked by, the “small” vowels e and i. The other mutes are not affected by such contact.18 The aspirate sounds are—ph = f, bh = v, th = h, dh and gh before e, i = y, ch = German and Scotch ch.
14 15 16 17 18 See Supplement to Outlines of Gaelic Etymology.
